1. Field of the invention
The present invention relates to an intake control device for an internal combustion engine.
2. Description of the prior art
In a known intake control device, a guide vane is disposed in an induction passage and arranged to be generally parallel to a cylinder axis. This vane is movable to vary the cross sectional area of the induction passage, and accordingly increases the velocity of the incoming charge under any given operating condition and directs the charge into the combustion chamber so as to swirl about the axis of the cylinder. However, this arrangement has suffered from the drawback that the variable opening through which the charge flows is substantially rectangular and oriented with the longitudinal axis thereof essentially parallel with the cylinder axis. This accordingly introduces the charge into the combustion chamber with a relatively weak flow component in the plane normal to the cylinder axis. This has lead to the formation of a swirl within the combustion chamber which all but disappears as the piston approaches TDC during the combustion stroke, at which time the swirl has the most value in promoting efficient combustion.